1. Field of the Invention
The present invention relates to optical devices and particularly to an optical device in which an optical element supported on an optical element supporting lead is sealed by a package having a lens through which light to or from the optical element passed on the surface at its position opposing said optical element together with other leads, a height from the rear surface of the optical element supporting lead at its portion for supporting the optical element is set to be smaller than a height from the front surface of the optical element to a top of the lens and outer ends of the leads including the optical element supporting lead are projected from one side surface of the package.
2. Description of the Related Art
FIG. 1 of the accompanying drawings shows a remote control light-receiving module for receiving an infrared remote control signal from a remote commander.
As shown in FIG. 1, the remote control light-receiving module is composed of a remote control signal reception monolithic IC 1 on or within which a photodiode and a signal processor are formed monolithically, an optical device supporting lead 2 to a tab or pad 3 of which the remote control signal reception monolithic IC 1 is bonded by die bonding, a connect wire 4 for connecting one electrode (e.g., a ground electrode) of the remote control reception IC 1 and the optical device supporting lead 2, and a package 5 for shielding the remote control reception IC 1 on the optical device supporting lead 2 together with an end of a connect wire connection side of another lead (not shown in FIG. 1), i.e., its inner end. The package 5 is made of a transparent resin through which infrared rays are passed and has a substantially rectangular solid shape. The package 5 includes a convex spherically-shaped lens 6 formed thereon. The above shielding is made by transfer molding for example.
The lens 6 is disposed at the optimum position of the remote control reception IC 1 such that infrared rays from the remote commander after the infrared rays were modulated by the remote control signal are converged on the surface of the remote control reception IC 1.
A plurality of (e.g., two) leads (not shown) other than the optical device supporting lead 2 are connected at their one ends to electrodes of the remote control reception IC 1 through connect wires (not shown), respectively. The respective leads including the optical device supporting lead 2 are projected at their ends opposing the connect wire side from one side surface (e.g., a left side surface in FIG. 1) of the package 5.
In the package 5 of the optical device, a thickness t3 ranging from the front surface of the optical device supporting lead 2 to the top surface of the lens 6 is considerably larger than a thickness t4 ranging from the rear surface of the optical device supporting lead 2 to the rear surface of the package 5. Each of the leads including the lead 2 is formed straight in the thickness direction without being bent. Therefore, assuming that t2 is a height from the rear surface of the package 5 to the rear surface of the optical device supporting lead 2 and that t1 is a height from the front surface of the optical device supporting lead 2 to a top 6p of the lens 6, then t1&gt;&gt;t2 is established.
The reason that the thickness t3 ranging from the front surface of the optical device supporting lead 2 to the top 6p of the lens 6 is considerably larger than the thickness t4 ranging from the rear surface of the optical device supporting lead 2 to the rear surface of the package 5 will be described below. Since the infrared rays modulated by the remote control signal from the remote commander have to be converged and focused on the surface of the remote control reception IC 1 by the lends 6, the thickness t3 should be set to a relatively large value of 3 mm or greater, for example. If, on the other hand, the thickness ranging from the rear surface of the optical supporting lead 2 to the rear surface of the package 5 is made large, air is difficult to escape upon resin shielding. As a result, a void tends to occur. Therefore, t1&gt;&gt;t2 has to be established.
The remote control reception module shown in FIG. 1 is difficult to be assembled into a printed circuit board, for example, automatically and therefore cannot be mass-produced.
Specifically, the remote control reception module is assembled into devices to be remote-controlled, such as a television receiver, a tape recorder or an air conditioner and so on. To be more concrete, outer ends of respective leads of the remote control reception module have to be fitted into predetermined through-holes of a printed circuit board and soldered to the interconnection of the printed circuit board. To insert the leads of the remote reception module into the through-holes manually is contradictory to a nowadays trend in which a demand for saving manpower and for improving mass-production is increased.
The same assignee of the present application has discussed use of an insertion machine for automatically inserting leads of an electric assembly into predetermined through-holes of a printed circuit board and properly bending ends of the leads after electric assemblies, such as capacitors, resistors or the like being wrapped by taping. An example of such insertion machine called a PANASERT (a product name, manufactured by Matsushita Electric Industry Co., Ltd.) is discussed to be used to assemble the remote control reception module to a printed circuit board.
The remote control reception module shown in FIG. 1 is difficult to be assembled to the printed circuit board even by the above-mentioned insertion machine. Moreover, it is frequently observed that the remote control reception module is not correctly assembled into the printed circuit board by the above-mentioned insertion machine. Therefore, the above-mentioned insertion machine cannot be used in actual practice.
The reason for this is that, when the above-mentioned insertion machine is used, the projected positions of the respective leads projected from the side surface of the package have to become coincident with substantially the central portion in the thickness direction of the package including the lens. That is, t1=t2 should be satisfied. However, since t1&gt;&gt;t2, the above-mentioned insertion machine cannot be used. Therefore, the usage of such remote control reception module cannot save manpower and is not suited to mass-produce electric equipments with the module.